1. Field of the Invention
The present invention relates to novel surfactant-impregnated, water-soluble fertilizer compositions which form dry, flowable products that are readily soluble and disperse easily in water. Furthermore, when solubilized, these compositions form a single phase solution over a wide range of fertilizer concentrations. The invention also relates to the use of said compositions when properly diluted to treat plant culture media and thereby improve certain properties thereof. More particularly, the instant invention relates to surfactant-compatibilizer-fertilizer compositions that i) at high fertilizer concentrations in water are extremely stable, i.e., do not phase separate; and ii) when diluted and applied to various plant culture media, improve both water and nutrient retention in said media.
2. Description of the Prior Art
Many methods have been suggested for enhancing the properties of plant culture media such as earth, horticultural soils, and various soil-mimicking, soil-less plant culture substrates. By xe2x80x9cenhancing the propertiesxe2x80x9d is meant that such techniques are capable, directly or indirectly, of promoting growth, increasing yield and/or improving the quality of the plant products grown therein.
To enhance plant culture media and/or to provide a substrate for the delivery of nutrients, various mineral-based materials have been used such as bentonite (frequently used for ameliorating light sandy soils); perlite; montmorillonites; heat-expanded naturally occurring clays, for example, vermiculite; and synthetically produced and natural silicate containing clays. Also, it has long been known that organic matter such as humus, composted bark or comminuted peat, e.g., a sphagnum, sedge, or hypnum peat in soil helps the soil to absorb and retain moisture and improves the ability of the soil surface to be penetrated by water.
Additional plant culture media performance enhancing materials are, of course, the fertilizers. In the horticulture and floriculture fields, especially in the production of greenhouse crops, water-soluble fertilizers are predominantly the fertilizers of choice. Fertilizers are complex mixtures of inorganic and, optionally, organic components which are capable of providing the elements required for plant growth. Such nutrient elements include, more particularly, N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, Mo, B, Co, S, and Na. Sustained-release nitrogen fertilizers have been selected, for example, from organic nitrogen compounds such as urea-formaldehyde condensate or crotonylidene-diurea, whereas ammonium, nitrate and amide nitrogen compounds are among the quick-acting constituents. Ammonium, potassium, magnesium and calcium phosphates that are soluble in water have proven to be useful for supplying plants with phosphate. Potassium is employed, for example, in the form of K2SO4, K2HPO4, KH2PO4, or KCl, but potassium magnesium sulfate is also often used. Magnesium may be employed in the form of various sulfate salts. Further fertilizer components are, for example, ammonium molybdate, iron sulfate, and zinc sulfate as well as boric acid and chelated trace elements. Suitable organic components that may be used as nutrients and/or as aggregates or fillers in plant growth media are biomasses from bacteria and fungi, urea, horn shavings, horn meal, blood and bone meal, seaweed powder and the like.
As an aside, fertilizer particles, in general, tend to exhibit at least one undesirable characteristic. Fertilizers per se tend to xe2x80x9ccakexe2x80x9d and the xe2x80x9ccakingxe2x80x9d interferes with their handling in bulk by the producer and by the end user. This fertilizer caking is believed to be caused by several factors, e.g., the formation of crystalline bridges according to which solid connections are formed at the points of contact among the granules. Alternatively, there may be capillary adhesion or bonding between the granules with a significant force often being necessary to break this adhesion or bonding. The cohesive forces will vary depending upon the storage conditions and other variables. The hygroscopic nature of the fertilizers also results in undesirable caking. In all cases, however, the caking causes a serious problem to which a completely satisfactory solution is lacking.
Surfactant wetting agents are commonly applied to plant culture media to enhance certain characteristics of the media; specifically initial water retention; water penetration; uniformity of wetting; and rewetting properties of the substrate. Nonionic and anionic surfactants are currently being marketed in the United States as wetting agents for plant culture media in greenhouse production. However, anionic surface active agents may be adversely affected by salts and other compounds normally contained in the media substrate. Furthermore, nonionic surfactants are less likely to deleteriously affect beneficial bacteria normally contained in the plant culture media, such as soil, than are the anionic surfactants. Also, nonionic surface active agents do not ionize and, because of this, are comparatively insensitive to electrolytes found in the media substrate. As a result of the above, and also due to their overall efficacy and phyto-safety, nonionic surfactants make up the greatest proportion of the wetting agents sold in the U.S. and, in fact, worldwide for plant culture media enhancement.
These nonionic wetting agents must have some significant solubility in water. Examples of such water-soluble materials are the following:
1) block-polymeric polyether glycols obtained, for example, by the addition of ethylene oxide on a condensation product of propylene oxide with propylene glycol;
2) alkylphenol-polyethylene oxide condensates which are condensation products of alkylphenols with ethylene oxide;
3) condensation products of aliphatic alcohols with ethylene oxide;
4) condensation products of ethylene oxide with the products resulting from the reaction of propylene oxide and ethylene diamine;
5) ammonia, monoethanol and diethanol amides of acyl fatty acids. These acyl moieties are normally derived from naturally occurring glycosides, but can be derived synthetically, and
6) various semi-polar, long chain nonionics including:
i) tertiary amine oxides,
ii) tertiary phosphine oxides; and
iii) sulfoxides
The two predominant groups of nonionic surfactants used in plant culture growing media are the alkylphenol polyethoxylates and the polyols; the preferred being the alkylphenol polyethoxylates.
When water-soluble fertilizer and nonionic wetting agents are to be transported to a plant culture media site, it is usually accomplished through aqueous irrigation delivery systems ending in an overhead spray or drip line. Water-soluble fertilizers may also be delivered via a range of subirrigation systems as a component of the standard irrigation process. Although both products are commonly used, each is often solubilized and kept as a concentrated solution in a separate stock tank and then pumped, diluted, and injected independently into the irrigation system. The reason that the fertilizer and the nonionic surfactants are solubilized in separate tanks is that concentrated fertilizer solutions are usually incompatible with horticultural wetting agents such as the nonionics. Incompatibility may be characterized as resulting in the formation of a multiphased solution, e.g., the separation of the surfactant from the concentrated aqueous fertilizer solution or the salting out of one or more of the fertilizer components. Incompatibility between water soluble fertilizers and wetting agent surfactants is of minor concern in diluted fertilizer solutions; however, as the concentrations increase to levels that are desired in stock tanks, i.e., especially from about 20 to about 50 weight percent, compatibility becomes a major concern.
The detergency art has taught that when nonionic surfactants are blended with alkylpolyglycosides as co-surfactants, there is realized increased corrosion inhibition, improved foam stabilization and enhanced laundry detergency over a wide range of fabrics (U.S. Pat. No. 4,483,780).
Co-surfactant blends of alkylpolyglycosides and an anionic surfactant such as alkyl naphthalene sulfonate have been added to pesticides to lower the surface tensions of these compositions (U.S. Pat. No. 5,516,747).
U.S. Pat. No. 5,385,750 discloses that the wetting ability of an aqueous mixture of an aliphatic glycoside and a material to be spread, such as a pesticide, especially when there is a need to penetrate an oily or waxy layer, is improved by the addition of a fatty alcohol. The fatty alcohol-glycoside adjuvants are also taught to be compatible with nitrogenous fertilizer products.
U.S. Pat. No. 5,258,358 teaches compositions for controlling undesired vegetation comprising a specific, novel herbicide, an alkyl polyglycoside, and at least one surfactant selected from the series comprising a fatty alcohol polyglycol ether sulfate, an alkydimethylamine oxide, an alkyldimethylbenzylammonium chloride and a coconut alkyldimethylaminoacetic acid or salt thereof.
A PCT publication by Zeneca Limited (WO 96/00010) discloses glyphosate herbicidal compositions which have xe2x80x9cgood activity in the absence of rain with effective rainfastnessxe2x80x9d by blending the herbicide with an adjuvant compositions comprising an alkylpolyglycoside and an ethoxylated alcohol.
Horticulturists and others working with plant culture media are currently faced with a dilemma viz whether or not to pre-treat the media with a wetting agent. By xe2x80x9cpre-treatxe2x80x9d is meant that a wetting agent, usually a nonionic surfactant has been intimately mixed with the plant culture media; the amount generally being equivalent to from 0.1-20 fluid ounces/cubic yard. One xe2x80x9cpre-treatsxe2x80x9d the media if one seeks to improve the uniformity of wetting and water retention of the media both initially (T=0) and over extended periods of time (with or without re-watering). Most premium commercial plant growth media are pre-treated with a surfactant. Secondary tier manufacturers and grower-produced culture media often do not contain a surfactant.
Thus, it is an object of this invention to provide solid, non-agglomerating or at least friable, particulate water-soluble fertilizer compositions which can be readily solubilized in water to form compatible, i.e., single phase concentrated solutions. Furthermore, it is another object of this invention to provide a process whereby the plant culture media water retention and uniformity levels after a short period of time (usually 7-10 days) and a dry-down (to less than 20% water) can be brought to essentially initial (T=0) pre-treat media levels with greatly enhanced retention of fertilizer nutrients.
The instant invention relates to agrochemical compositions which may comprise, consist of, or consist essentially of a bioactive chemical composition, especially a water-soluble fertilizer and a preferred surfactant system, especially one comprising an alkylphenol ethoxylate or a polyol surfactant or mixtures thereof and an alkylpolyglycoside compatibilizer.
The invention also relates to a process for obtaining and sustaining high water retention and uniformity levels of plant culture media that has not been pre-treated as compared to that achievable with pre-treated media, together with the enhancement of fertilizer nutrient levels over that heretofore realizable with similar pre-treated media. This process comprises the application of the aforedescribed fertilizer compositions of this invention to media that has not been pre-treated. Additionally, this technology enables an end user to formulate a single product in one tank concentrate rather than having to purchase and maintain two or more separate tanks and control the blending of the individual components to avoid the aforementioned phase separation risk. Additionally, a significant cost savings can be realized by plant culture media users by i) not having to pre-treat the media prior to use and ii) reducing the amount of fertilizer leaching that occurs on initial liquid fertilizer applications.
It is also contemplated that the invention comprises enhancing the availability of nutrients in the root zone of plants by applying the surfactant system of this invention to solid plant culture media, such as soil that is treated contemporaneously with water-soluble fertilizer.